Shares in Pike River Coal's main shareholder, New Zealand Oil Gas, have fallen by a third since they resumed trading on the stock exchange on Tuesday.
The listed energy explorer owns 29 percent of Pike River Coal. Trading had been suspended since an explosion at the West Coast mine on Friday.
Its shares were placed on a trading halt before the market opened on Monday, while the company established how it would be affected by Friday's explosion.
The suspension was lifted shortly after 1pm and its shares have since fallen 35 cents to a five-year-low of 85c.
Shares in Pike River Coal have been suspended on the New Zealand and Australian stock exchanges and are likely to remain so for much longer.